Bovine serum albumin (BSA) heavily conjugated with a lipid (dodecanoic acid) selectively stimulates a type of cell-mediated immunity, delayed hypersensitivity (DTH), instead of the antibody responses usually produced by stimulation with native BSA. The experiments proposed in this project will include consideration of some of the physical, chemical and immunologic properties of chemically modified BSA preparations which selectively stimulate DTH. The cellular basis of the action of these antigens will be studied in vivo and in vitro. In further experiments, we will prepare and evaluate a series of natural and synthetic materials which may serve as adjuvants to selectively enhance the production of DTH. These experiments hopefully will develop both a rationale and a protocol for stimulating strong, sustained DTH to BSA and other antigens. Parallel studies will use the information gained from these basic experiments in an attempt to stimulate DTH against purified tumor antigens and to cause regression of established tumors by immunologic methods. Selected tumor antigens will be chemically modified and injected into appropriate animals according to the protocols found most effective in selectively stimulating DTH to BSA. Current studies are directed towards identification of a particularly potent enhancing factor found in the sera of some hamsters bearing SV40 induced sarcomas.